1. Technical Field
The present invention relates to cleaning web devices in the fixing station of electrostatographic printing apparatuses, such as electrostatic photocopying machines, printers, and facsimile machines; in particular the present invention relates to the recycling use of such cleaning web devices.
2. Description of Related Art
In electrostatographic printing devices, printing sheets carrying a toner-developed image are conveyed to a fixing station typically having a heating roller against which a pressure roller presses. The toner image is fuse-fixed onto the printing sheets as they are nipped by the pair of rollers in conveyance to the fixing station. In the fixing process, toner particles thus cling to the surface of the heating roller, and consequently a cleaning device is provided in the fixing station for cleaning the heating roller.
Toner that does not get cleaned from the surface of the heating roller may stick to the surface of the pressure roller due to its different separative properties from the heating roller. Further, in double-sided image fixing processes in electrostatographic printing devices, toner may stick to the surface of the pressure roller. Consequently, a cleaning device for the pressure roller is also provided.
Examples of such cleaning devices include unit devices in which a cleaning web that is prepared by impregnating a heat-resistant paper or the like with a parting agent such as silicone oil is stretched from a web feed reel to a web take-up real, bringing one surface of the cleaning web into contact with the roller surface to be cleaned. The cleaning web is wound at a predetermined rate, and as the roller it contacts rotates, toner sticking to the roller surface is stripped off by the cleaning web.
A problem in thus employing a cleaning web, however, is that in bringing the web into cleaning contact with the roller a major portion of the parting agent contained in the web is applied to the roller surface. Accordingly, wherein after using one side of a cleaning web, the other side is to be used for another roller cleaning, the amount of parting agent applied to the surface of the roller is insufficient. Therefore, under the present circumstances only one side of the cleaning web is generally used and then it discarded.
Thus disposing of the cleaning web is, however, quite uneconomical.
Toward overcoming the forgoing problems, JP-A-140830/1995, in pursuing economy of use, discloses a technique in which a used cleaning web is reversed and re-extended between web feed and web take-up sections, and in order to compensate for the lack of parting agent remaining for application to the roller surface to be cleaned, the winding speed after reversing the web is increased over that prior to reversing, in order to equalize the quantity of parting agent applied by either side of the web. Unfortunately, it is very difficult to adjust the amount of parting agent applied in this manner; moreover the structure entailed is complex, increase the overall cost of the cleaning web unit.